Papers by Author: Hong Chi Zhao

Abstract: In this article, graft copolymerization of styrene (St) onto cassava starch via potassium diperiodatonickelate (IV)–starch redox system as an initiator was investigated in an alkaline medium. The effects of reaction variables were investigated, and the grafting conditions were optimized. The equation of the polymerization rate were obtained, Rp= k•C^1.02 (St)•C^0.53 (Ni（IV）). The graft copolymer was characterized with Fourier-transform infrared spectra analysis (FTIR) and scanning electron microscopy (SEM). FTIR spectra indicated the presence of PSt-g-starch copolymer. SEM micrographs also showed PSt adhering on the starch.

Abstract: Polyvinylamine (PVAm) was synthesized by Hofmann degradation of polyacrylamide (PAM). The thermal properties of the Polyvinylamine hydrochloride (PVAm•HCl) were studied by differential scanning calorimeter (DSC). The degradation rate (a) decreased with increasing weight-average molecular weight (Mw) of PAM and decreasing amount of NaOH, and a were the better values when the concentration of PAM was 5% and the amount of NaClO was 10 mL. DSC curves showed that the glass transition temperature (Tg) of PVAm•HCl increased with increasing Mw of PAM, concentration of NaClO and decreasing concentration of NaOH. Tg of PVAm•HCl appeared the minimum value when the concentration of PAM was 5.0%.

Abstract: Copolymers of styrene (St), n-butyl acrylate (BA) and vinyltrimethoxysilane (VTMS) have been synthesized by emulsifier-free emulsion copolymerization using ammonium persulfate (APS) as initiator. Acrylic acid used as functional monomer was also added into the emulsion polymerization system. The effects of varying the concentrations of initiator and VTMS as well as the polymerization temperature on the polymerization conversion were investigated in detail. The copolymer was characterized by Fourier transform infrared spectrometer (FTIR). Copolymerization of VTMS with St and BA was confirmed by the appearance of an absorption peak between 1000 cm-1 to 1200 cm-1 (due to Si-O-C bonds) in the IR spectrum. The siloxane segments in the copolymer chain underwent hydrolysis and self-condensation, resulting in a change in the structure of the copolymers from linear into a cross-linked network. As a result, the organic and inorganic hybrid material was formed. The water absorption of emulsion decreased with increasing VTMS concentration. The polymerization conversion increased with increasing polymerization temperature, molar concentration of initiator and decreased with increasing molar concentration of VTMS.

Abstract: Copolymers of styrene (St) and vinyltrimethoxysilane (VTMS) have been synthesized by emulsifier-free emulsion copolymerization using ammonium persulfate (APS) as initiator. Acrylic acid used as functional monomer was also added into the emulsion. The effects of varying the concentrations of initiator and VTMS as well as the polymerization temperature on the polymerization conversion and rate were investigated in detail. The copolymer was characterized by Fourier transform infrared spectrometer (FTIR). Copolymerization of VTMS with St was confirmed by the appearance of an absorption peak between 1000 cm-1 to 1200 cm-1 (due to Si-O-C bonds) in the IR spectrum. The siloxane segments in the copolymer chain underwent hydrolysis and self-condensation, resulting in a change in the structure of the copolymers from linear into a cross-linked network. As a result, the organic and inorganic hybrid materials were formed. The polymerization rate increased with increasing polymerization temperature, molar concentration of initiator and decreased with increasing molar concentration of VTMS. The apparent activation energy and kinetic features of the polymerization system were also obtained.

Abstract: Polystyrene (PS) was synthesized by emulsion polymerization. 1,4-bis(chloromethoxy)butane (BCMB) was synthesized using 1,4-butanediol, formaldehyde and phosphorus trichloride as raw material. The linear poly(p-chloromethyl styrene) (PS-Meyl-Cl) was prepared high effectively using BCMB and anhydrous aluminium trichloride as the chloromethylation reagent and catalyst, respectively. In this method, carcinogenic compound (chloromethyl ether etc.) was avoided. The resultant polymers were characterized by gel permeation chromatography (GPC), Fourier transform infrared spectrometer (FTIR) and thermogravimetric analyzer. The results show that the molecular weight (Mw) of PS is big. BCMB has been prepared because of the strong absorption band observed at 1130cm-1 (due to C-O-C bond stretching vibration) and two new bands at 640 and 1315cm-1 (due to the bending vibration of C-Cl bond and stretching vibration of C-H bond in -CH2Cl, respectively). Chloromethyl groups were introduced into benzene ring of PS because of the appearance of the absorption peaks at 676 and 1419cm-1 (due to the bending vibration of C-Cl bond and stretching vibration of C-H bond in -CH2Cl, respectively) in the FTIR spectra. The thermal stability of PS-Meyl-Cl was decreased with increasing chloromethyl group. Moreover, there are two decomposing stages. The reaction condition is gentle and the operation is safe, simple and economical.

Abstract: Polyvinylamine (PVAm) and polyvinylamine chloride (PVAm•HCl) were synthesized by Hofmann degradation of polyacrylamide (PAM). The reaction condition is gentle and the operation is safe, simple and economical so that it is a good reaction method. The chemical structures and thermal properties of the polymers were studied by Fourier transform infrared spectrometer (FTIR), nuclear magnetic resonance spectrometer (NMR), X-ray diffractmeter (XRD) and thermogravimetric analyzer (TGA). Synthesis of PVAm•HCl was confirmed by the intensities of the characteristic peak of -CONH2 decreased and the appearance of a new absorption peak at 1530cm-1 (due to N-H bond of -NH3+ ) in the FTIR spectrum, the appearance of the characteristic absorption peaks of carbon atoms in the 13C NMR spectrum, the appearance of chemical shift assignments of proton in 1H NMR spectrum and the appearance of characteristic dispersing diffraction peak between 22.5° to 25.2° in the XRD spectrum, respectively. PAM had three decomposing stages, but PVAm•HCl had two decomposing stages. TG curve of PAM and PVAm•HCl showed that the initial decomposition temperature were 190oC and 140oC, respectively. The thermal stability of PVAm•HCl was poorer than that of PAM.

Abstract: Poly(allylamine phosphate) (PAP) was synthesized by solution polymerization using allylamine phosphate (AP) as monomer, 2,2’-azo-bis-2-amidinopropane dihydrochloride (AAP•2HCl) as initiator, respectively. PAP reacted with concentrated hydrochloric acid and it converted into poly(allylamine hydrochloride) (PAH). The effects of varying the concentrations of initiator and monomer on the polymerization conversion were investigated in detail. The chemical structure and thermal property of the polymer were studied by Fourier transform infrared spectrometer (FTIR), nuclear magnetic resonance spectrometer (NMR), thermogravimetric analyzer (TGA), differential scanning calorimeter (DSC), X-ray diffractmeter (XRD), respectively. PAH was prepared because of the disappearance of the stretching vibration absorption peaks and deformation vibration absorption peak of C-H bonds in -C=CH2 at 3020cm-1, 3085cm-1 and 1310cm-1 in the FTIR spectra. The three peak areas and their chemical shifts were consistent with the three kinds of hydrogen atoms in polymer formula in 1H NMR spectrum, which proved that PAH was synthesized. PAH had three decomposing stages and it decomposed completely at 700oC. The glass transition temperature (Tg) of PAH increased with decreasing concentration of initiator. The conversion of monomer increased with the increasing concentrations of initiator and monomer.

Abstract: Polystyrene (PS) was synthesized by emulsion polymerization. The linear chloroacetylated PS was prepared high effectively by Friedel-Crafts acetylation of PS using chloroacetyl chloride and anhydrous aluminium chloride as chloroacetylation reagent and catalysts, respectively. The structure of chloroacetyl group is similar to that of chloromethyl group. In this method, carcinogenic compound (chloromethyl ether etc.) was avoided and the reactions of secondary cross link and multi-substitute could be eliminated. The resultant polymers were characterized by Fourier transform infrared spectrometery (FTIR) and thermogravimetric analysis. The effects of reaction conditions on chloroacetylation were studied, and the optimum reaction conditions were obtained. Chloroacetyl group was introduced into benzene ring of PS because of the appearance of the absorption peaks at 1695cm-1 (due to C=O bonds) and 644cm-1 (due to C-Cl bonds) in the FTIR spectrum. The thermal stability of the chloroacetylated PS was decreased with increasing chloroacetyl group. Moreover, there were two decomposing stages. The glass transition temperature of chloroacetylated PS increased with substitution value increasing. The effects of the reaction conditions such as reaction temperature, the solvent amount and the concentration of chloroacetyl chloride and anhydrous aluminium chloride on the chloroacetylation of PS were obvious. The certain loading can be controlled when it is lower than the maximum loading of chloroacetylated PS. The reaction condition is gentle and the operation is safe, simple and economical so that Friedel-Crafts acetylation of PS is an ideal reaction method.

Abstract: In this study the vapour phase surface graft polymerization of acrylonitrile (AN) onto poly(ethylene terephthalate) (PET) film was conducted with benzoyl peroxide (BPO) as an initiator. Effects of reaction time and quantity of BPO on the polymerization were investigated. With the prolongation of reaction time, the graft polymerization took place rapidly at first, then slowed down, and leveled off. With the increase of BPO, the graft yield increased, then remained unchanged, and lastly began to decrease. The surface topography structure of the grafted PET film was observed by SEM. Grafted PET film was characterised by FTIR spectra, SEM photographs and contact angle measurement.

Abstract: Copolymerization of MAn and CHDDVE was conducted by using azobisisobutyronitrile (AIBN) or benzoyl peroxide (BPO) as the initiator, ethyl acetate (EA) or n-butyl acetate (BA) as the solvent, and n-hexane as the precipitator. Effects of several factors on monomer conversion were studied, such as reaction time, reaction temperature, composition of the monomer feed (MAn/CHDDVE) and initiator concentration. Molecular weight and its polydispersity and polymer material morphology were characterized by gel permeation chromatography (GPC) and transmission electron microscope (TEM) technologies, respectively. It was demonstrated that CTC was formed in MAn/CHDDVE system, based on ultraviolet-visible spectroscopy (UV-vis) analysis. The product was alternating copolymer with high crosslinking degree, so it could not be dissolved in common solvents, e.g. water, chloroform, N, N-dimethyl formamide (DMF), tetrahydrofuran (THF) and acetone (Ac).